Preparation of costus root oil and the products thereof



Unite States Patent PREPARATION OF COSTUS ROOT OIL AND THE PRODUCTS THEREOF Govind Ramchandra Kelkar and Sasanka Chandra Bhattacharyya, Poona-8, India, assignors to Council of Scientific and Industrial Research, New Delhi, India No Drawing. Filed Aug. 19, 1958, Ser. No. 755,887

1 Claim. (Cl. 2'60-236-6) Costus oil is valued in high grade erfumery preparations.

It is obtained from the roots of Saussurea lappa C. B. Clarke. Various methods have been used for isolation of the oil. In earlier years steam distillation was the method generally employed, which has also been used by some of the recent workers. The oil is rich in lactonic Y constituents which are not so volatile in steam. Moreover, some of the lactonic constituents are thermolabile and easily polymerised on protracted heating around 60-70" C. or more quickly at higher temperatures. For these reasons a few workers have used solvent extraction methods using alcohol, benzene and petroleum ether etc. Peculiarly enough, probably due to lack of full appreciation of the instability of the lactonic components, many of the workers, however, did not take adequate care for the control of the temperature during the removal of solvent, or subjected this thermolabile oil to vacuum distillation and collected fractions boiling at l90-210 C./11 mm. and processed these fractions for the isolation of the lactones. Considering the boiling points of these lactones, the bath temperature in these cases must have been as high as 210250 C. At such high temperatures these thermolabile components for the most part polymerise and undergo decomposition. Consequently, the lactonic components examined by different workers are secondary derived products and not the original lactones as they exist in the root. Moreover, even the method of isolation of the costus root oil through solvent extraction has.

not been standardised.

This invention has for its object an improved process .whereby the costus root oil and the original lactones as they exist in the root may be isolated in the form in which they exist in the root, i.e. without causing polymerisation or decomposition of the thermolabile components.

With this object in view, this invention broadly consists of an improved process for. the extraction of costus root oil and the products thereof, which consists in treating the powdered costus roots with petroleum ether (40- 60 C.) at room temperature, separating the petroleum ether extract from the plant pulp by filtration and removing the solvent from the said extract under vacuum at a bath temperature of about 40 C.

The invention also includes the further-step of isolating from the costus root oil prepared by the improved process, a lactone called costunol-ide by keeping the said oil at room temperature or in a refrigerator, either as such or in the presence of a small quantity of petroleum ether.

The invention also includes the further step of isolating from the residual oil after the removal of costunolide, a lactone mixture by keeping the said residual oil mixed with petroleum ether in a deep freeze 15 to C.)

for about 20 hours.

The following example illustrates'the manner in which this invention may be carried into practice:

ice

Step 1.-Costus roots obtained from Kashmir or Kulu (Punjab) were powdered to a fine mesh using mechanical disintegrators.

Step 2.The powdered root as in Step 1 (24 kg.) was mixed with low boiling petroleum ether (40-60 C., 45 l.) in a narrow-mouthed stainless steel vessel and stirred mechanically with a powerful motor stirrer for about 4 hours at room temperature and the contents then were left standing overnight, for the sake of convenience.

Step 3.--The extract as in Step 2 was then filtered. The residual plant pulp was subjected to two more similar extractions but using only 30 l. of petroleum ether each time.

Step 4.The combined filtrates as in Step 3 were poured into a double jacketed stainless steel vessel fitted with adequate condensers and connection for vacuum. The jacket temperature of the above vessel was maintained at about 40 C. and the solvent removed under reduced pressure. The solvent recovery was about 60 percent. It could be higher if more eificient condensers and cooling system were used. The residue left in the vessel contained the costus root oil.

Step 5.From the costus root oil concentrate as in Step 4, the last trace of petroleum ether was then removed by using a good vacuum pump at a bath temperature of about 40 C. Traces of suspended matter were removed by filtration under vacuum. The yield of oil from the Kashmir variety was about 6.2 percent. It has the following properties. Colour clear and pale brown, d 1.048; [a] +31.47; n 1.5288.

The Kulu variety of the roots when processed as above gave an oil in about 3.7 percent yield.

Step 6.Costus root oil as obtained in Step 5 on keeping at room temperature or in a refrigerator either as such or in presence of small quantity of petroleum ether (40-60 C.) deposited crystals of costunolide which on crystallisation melted at 108 C. The residual oil after initial removal of costunolide was mixed with petroleum ether (40-60 C., 1.5 times the volume of oil) and kept in a deep freeze (-15 to 20 C.) for about20 hours. Crystals of the residual lactone mixture were then filtered under suction and washed twice with ice cold petroleum ether; melting point 40 to 60 C. The yield of total lactone costunolide and (the residual lactone mixture was about 250 g. from about 450 g. of oil.

The Kulu variety of costus root oil also gave the same lactones.

What we claim is:

A process for the extraction of an unaltered, heat sensitive lactone of costus root oil and the products thereof, said lactone being characterized by a melting point of 108 C. in pure form, comprising the critical steps of (1) treating the powdered costus roots at room temperature with a fraction of petroleum ether having a boiling .point of from 4060 C., (2) separating the petroleum ether extract from the plant pulp by filtration, and (3) removing the solvent from the said extract under vacuum at a bath temperature of about 40 C.

References Cited in the file of this patent UNITED STATES PATENTS Young et al. Jan. 25, 1938 OTHER REFERENCES 

